(1) Field of the Invention
The invention relates to an elastomeric launch system, and more specifically to a submarine low-noise projectile launching system.
(2) Description of the Prior Art
Existing submarine weapon launch systems are mechanisms which eject a torpedo or other device from the submarine by pumping a working fluid, usually seawater, behind the device in the launch tube. The two most common launch devices are the ram pump and turbine pump ejection systems. Both systems are mechanically complex and tend to radiate noise into the surrounding fluid medium.
A ram pump launch apparatus converts potential energy from compressed air stored in a flask into working fluid kinetic energy. The ram pump system utilizes a massive piston apparatus to transfer sufficient working fluid, such as seawater, to launch a projectile. The mechanical friction and the mass of the piston act to reduce system efficiency and to produce substantial radiated noise. The ram pump system requires frequent maintenance because the system includes numerous mechanical components, in addition to the piston assembly.
A turbine pump launch apparatus also converts potential energy in the form of compressed air stored in a flask into kinetic energy of a working fluid. An air turbine drive unit is joined with a rotary impeller pump via a speed reduction unit. The turbine pump system is costly because of the complexity of the required mechanical components and is also noisy due to dynamic interaction of many of the system components.
In U.S. Pat. No. 4,848,210, issued Jul. 18, 1989 to Laurent C. Bissonnette, there is shown and described an elastomeric impulse energy storage and transfer system. The '210 system as shown is adapted to a torpedo launch system wherein an elastomeric bladder is distended by filling it with pressurized working fluid. When an impulse of energy is desired the elastomeric bladder discharges the working fluid to quietly eject a projectile from the launch system into the surrounding liquid. The elastomeric bladder used is generally spherical containing, when expanded, volume sufficient to fill the launch tube and the launchway forward of the launch tube.
Following expulsion of seawater from the elastomeric bladder, a low pressure region forms at the mouth of the launch tube because of the finite nature of the fluid volume available in the bladder and the competing momentum of the fluid exiting the launch tube. This low pressure region is undesirable because it causes excessive noise due to cavitation. To prevent the pressure differential and the noise associated therewith, additional seawater must be available to the launch tube after the elastomeric bladder has been discharged.